cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-3 of 3 results.

A193220 Denominators of the fourth row of Akiyama-Tanigawa algorithm leading to Bernoulli numbers A164555(n)/A027642(n).

Original entry on oeis.org

1, 30, 20, 35, 84, 84, 120, 495, 55, 286, 1092, 455, 280, 2040, 816, 969, 855, 1330, 1540, 5313, 1012, 2300, 7800, 2925, 819, 10962, 4060, 4495, 7440, 5456, 5984, 19635, 1785, 7770, 25308, 9139, 4940
Offset: 0

Views

Author

Paul Curtz, Jul 18 2011

Keywords

Comments

Denominators of row k=3 of the table in A051714.

Examples

			The third row is 0, 1/30, 1/20, 2/35, 5/84, 5/84, 7/120, 28/495, 3/55, 15/286, 55/1092, 22/455, 13/280, ...
		

Crossrefs

Cf. A194531 (numerators).

Programs

  • Maple
    read("transforms3");
    L := [seq(1/n,n=1..40)] ;
    L1 := AKIYATANI(L) ; L2 := AKIYATANI(L1) ; L3 := AKIYATANI(L2) ;
    apply(denom,%) ; # R. J. Mathar, Aug 20 2011
  • Mathematica
    a[0, k_] := 1/(k+1); a[n_, k_] := a[n, k] = (k+1)*(a[n-1, k] - a[n-1, k+1]); Table[a[3, k], {k, 0, 36}] // Denominator (* Jean-François Alcover, Sep 18 2012 *)

A100652 Denominator of 1 - Sum_{i=1..n} |Bernoulli(i)|.

Original entry on oeis.org

1, 2, 3, 3, 10, 10, 105, 105, 70, 70, 1155, 1155, 1430, 1430, 2145, 2145, 24310, 24310, 4849845, 4849845, 58786, 58786, 2028117, 2028117, 965770, 965770, 1448655, 1448655, 28007330, 28007330, 100280245065, 100280245065, 66853496710, 66853496710, 100280245065
Offset: 1

Views

Author

N. J. A. Sloane, Dec 05 2004

Keywords

Comments

Contribution from Paul Curtz, Aug 07 2012 (Start):
Take a(0)=1. Then instead of the Akiyama-Tanigawa algorithm we create the extended (or prolonged) Akiyama-Tanigawa algorithm using A028310(n)=1,1,2,3,4,5,... instead of A000027(n)=1,2,3,4,5,.. .
Hence the array (A051714 with an additional column)
2, 1, 1/2, 1/3, 1/4,
1, 1/2, 1/3, 1/4, 1/5,
1/2, 1/6, 1/6, 3/20, 2/15, A026741(n+1)/A045896(n+1)
1/3, 0, 1/30, 1/20, 2/35, A194531(n)/A193220(n)
1/3, -1/30, -1/30, -3/140, -1/105. A051722(n)/A051723(n).
a(n) is the denominator of the (first) column before the Akiyama-Tanigawa algorithm leading to the second Bernoulli numbers A164555(n)/A027642(n). See A176672(n).
(End)

Examples

			1, 1/2, 1/3, 1/3, 3/10, 3/10, 29/105, 29/105, 17/70, 17/70, 193/1155, 193/1155, -123/1430, -123/1430, -2687/2145, -2687/2145, -202863/24310, -202863/24310, -307072861/4849845, ... = A100651/A100652.
		

Programs

  • Mathematica
    Denominator[1-(Accumulate[Abs[BernoulliB[Range[0,40]]]])] (* Harvey P. Dale, Jan 28 2013 *)

A230262 Numerators of Akiyama-Tanigawa algorithm applied to harmonic numbers, written by antidiagonals.

Original entry on oeis.org

1, 3, -1, 11, -2, 1, 25, -3, 1, 0, 137, -4, 3, 1, -1, 49, -5, 2, 1, -1, 0, 363, -6, 5, 2, -3, -1, 1, 761, -7, 3, 5, -1, -1, 1, 0, 7129, -8, 7, 5, 0, -4, 1, 1, -1, 7381, -9, 4, 7, 1, -1, -1, 1, -1, 0, 83711, -10, 9, 28, 49, -29, -5, 8, 1, -5, 5
Offset: 0

Views

Author

Paul Curtz, Nov 09 2013

Keywords

Comments

Leading column gives the Bernoulli numbers: A027641(n)/A027642(n). In A051714, A164555 must be written instead of A027641.

Examples

			Numerators of
1,    3/2, 11/6, 25/12,...
-1/2, -2/3, -3/4,  -4/5,...
1/6,   1/6, 3/20,  2/15,... =A026741(n+1)/A045896(n+1)
0,    1/30, 1/20,  2/35,... =A194531/A193220.
		

Crossrefs

Programs

  • Mathematica
    t[1, k_] := HarmonicNumber[k]; t[n_, k_] := t[n, k] = k*(t[n-1, k] - t[n-1, k+1]); Table[t[n-k+1, k] // Numerator, {n, 1, 12}, {k, n, 1, -1}] // Flatten (* Jean-François Alcover, Nov 15 2013 *)

Extensions

More terms from Jean-François Alcover, Nov 15 2013
Showing 1-3 of 3 results.